1. Field of the Invention
The present invention relates generally to a tone generator for use in such apparatuses for generating tones as electronic musical instruments and amusement appliances. More particularly, the present invention relates to a tone signal processing apparatus for suitable in saving the power consumption of these instruments and appliances.
2. Description of Related Art
With the recent enhancement in the performance of tone generators for use in electronic musical instruments for example, the maximum number of sounding channels and the level of operating clock frequencies grow steadily. This inevitably causes an increase in the number of transistors and the number of transistor switching operations in a unit time in tone generator LSIs for example, thereby presenting a problem of the proportionally increased power consumption in these LSIs. Especially, with battery-driven electronic musical instruments, the large power consumption presents a serious problem which must be solved to provide an operating life long enough for the general use of these musical instruments.
With CPUs for use in personal computer for example, a technology is known by which the clock frequency is adjusted in accordance with occasional processing loads. However, this technology has a drawback of complicating the configuration of clock circuits.
It is therefore an object of the present invention to provide a tone signal processing apparatus having a relatively simple configuration but capable of reducing the power consumption in accordance with processing load.
According to the invention, an apparatus is constructed for processing a music tone signal in response to a clock signal at each sampling period. The apparatus comprises a clock generator that generates the clock signal, a signal processor operable in synchronization to the clock signal for time-divisionally processing a plurality of music tone signals through a plurality of channels within one sampling period, and a clock controller being operative during a supply duration allocated within one sampling period for supplying the clock signal to the signal processor from the clock generator to thereby operate the signal processor, and being operative during other than the supply duration within one sampling period for stopping the supplying of the clock signal to the signal processor to thereby suspend the signal processor.
Preferably, the inventive apparatus further comprises an allocating device that allocates a predetermined supply duration within one sampling period, and a specifying device that specifies a detail of processing of the music tone signals in accordance with the predetermined supply duration so that the signal processor can complete the processing of the music tone signals within the predetermined supply duration. In such a case, the allocating device allocates the predetermined supply duration based on a predetermined number of channels through which music tones are generated concurrently by the processing of the music tone signals. Otherwise, the allocating device allocates the predetermined supply duration based on a predetermined number of steps by which a program is executed stepwise for processing the music tone signals. Further, the specifying device specifies the detail of the processing of the music tone signals in terms of a number of channels through which the music tone signals are processed for concurrent generation of music tones. Otherwise, the specifying device specifies the detail of the processing of the music tone signals in terms of a kind of a program selectably executed by the signal processor in the processing of the music tone signals.
Preferably, the inventive apparatus further comprises a specifying device that specifies a detail of processing of the music tone signals, and an allocating device that allocates a supply duration within one sampling period in accordance with the specified detail of the processing so that the signal processor can complete the specified detail of the processing of the music tone signals within the allocated supply duration. In such a case, the allocating device allocates the supply duration in accordance with the specified detail of the processing in terms of a predetermined number of channels through which music tones are generated concurrently by the processing of the music tone signals. Otherwise, the allocating device allocates the supply duration in accordance with the specified detail of the processing in terms of a predetermined number of steps by which a program is executed stepwise for processing the music tone signals. Further, the specifying device specifies the detail of the processing of the music tone signals in terms of a number of channels through which the music tone signals are processed for concurrent generation of music tones. Otherwise, the specifying device specifies the detail of the processing of the music tone signals in terms of a kind of a program selectably executed by the signal processor in the processing of the music tone signals.
Preferably, the signal processor processes the music tone signal in such a manner that waveform data of a designated timbre is read out to generate the music tone signal at a designated pitch. Otherwise, the signal processor processes the music tone signal in such a manner that waveform data is read out to generate the music tone signal and the generated music tone signal is subjected to filter processing. Alternatively, the signal processor processes the music tone signal in such a manner as to control an amplitude of the music tone signal. Otherwise, the signal processor processes the music tone signal in such a manner as to impart an effect to the music tone signal.